Alkylbenzene sulfonate color and odor inhibition



United States Patent Oil ice 3,297,748 ALKYLBENZENE SULFONATE COLOR AND ODOR INHIBITION John B Wilkes, Albany, Calif., assignor to Chevron Research Company, a corporation of Delaware No Drawing. Filed June 13, 1963, Ser. No. 287,489 2 Claims. (Cl. 260-505) This invention relates to an improved method for the preparation of branched-chain alkylbenzene sulfonate detergents. More specifically, this invention relates to the preparation of branched side-chain alkylbenzene sulfonate detergent by the sulfonation of branched-chain alkylbenzenes with oleum in the presence of color and odor inhibiting amounts of acetic acid and a lower alkylbenzene.

The active ingredient in most detergents in household use are alkylated aryl sulfonates. For aesthetic reasons, color and odor properties of these detergents are, therefore, of particular importance, for, although color and odor bodies appear to have no other effect on the properties of the detergent, these properties do have a large effect on the acceptance of the product by the trade.

While many process methods have been proposed for the treatment of the finished product for the elimination of color and odor bodies from the crude alkylbenzene sulfonates, the more practical solution of the problem appears to be the substantial inhibition of the production of these bodies in the formative process.

The concurrent formation of color and odor bodies is a particular problem in the conversion of branched-chain alkylbenzene feeds to the corresponding alkylbenzene sulfonates, by use of oleum under sulfonating conditions.

In general, the present invention is useful in the sulfonation of alkylbenzene compounds in which the alkyl group contains from 9 to 18 carbon atoms, although relatively smaller amounts of dialkylbenzene and of higher and lower molecular Weight alkylbenzenes may be present in admixture. As is known in the art, alkylbenzene feeds having side chains averaging from about 12 to 15 carbon atoms per side-chain group yield superior detergents. The present invention is particularly advantageous in the preparation of this molecular weight range detergent sulfonate and especially with those branched .sidechain alkylbenzene feeds having from 1 to about 6 lower alkyl, usually methyl, side-chain branching groups per molecule. Representative branched side-chain alkylbenzene hydrocarbon feeds are the detergent alkylates obtained by the alkylation of benzene with polypropylene obtained by the phosphoric and sulfuric acid catalyzed polymerization of propene, including propylene tetramer benzene alkylate, propylene pentamer benzene alkylate, and the like. Other useful feeds include benzene alkylate obtained by the use of triisobutylenes, mixed polymers of propene and butenes, isobutene trimer benzene alkylate, and the like.

It has now been found that the color and odor characteristics of branched-chain alkylbenzene sulfonates having from 9 to 18 carbon atoms per side-chain group are greatly improved when the corresponding alkylbenzene hydrocarbon is sulfonated with oleum in the presence of from 0.5 to 6.0 percent each, based upon the weight of the alkylbenzene, of acetic acid, and of a lower monoalkylbenzene hydrocarbon having from 1-7 carbon atoms per alkyl group. Detergent sulfonates prepared in this manner show marked reduction in color body content, being as much as 50%, based upon standard runs. At the same time, the product produced by the present process 3 ,297,748 Patented Jan. 10, 1967 was found to have superior odor qualities, based upon odor ratings made by subjective panel testing.

'By sulfonation is meant the treatment of alkylbenzenes with concentrated sulfuric acid, and particularly with concentrated sulfuric acid-sulfur trioxide mixtures, thereby to produce the corresponding alkylbenzene sulfonic acids. Preferably, the present process contemplates the use of oleum having from about 5 to 28 percent sulfur trioxide content, by Weight. In general, sulfonation reac tion temperatures useful in the process range from about 50 to 150 F.; and, as is known in the art, from about a stoichiometric amount to about a 20 percent excess of the sulfonating agent, based upon the alkylbenzene, is preferably used. Usually, the sulfur trioxide in the oleum mixture is the sulfonation agent consumed, although the sulfuric acid may also be consumed to the point where the residual sulfuric acid medium has been reduced through the production of water in the alkylation reaction to about 96 percent sulfuric acid.

While the presence of minor amounts of any lower alkylbenzene and similar minor amounts of acetic acid during oleum sulfonation of branched-chain alkylbenzene detergent alkylates results in appreciable color and odor improvements of the product, those lower alkylbenzenes represented by the formula:

wherein R and R may be methyl, ethyl, and propyl, are particularly effective in connection with the presence of acetic acid in the inhibition of color and odor body formations. In some measure at least, the reason for the superiority of the above preferred lower alkylbenzenes is believed associated with the ease of carbonium ion formation of these materials under the oleum sulfonation conditions.

The examples following are given for purposes of illustration, and it is to be understood that the invention is not to be limited to the specific conditions or details set forth, but only insofar as such limitations are specified in the appended claims.

Examples The sulfonations from which the following experimental results were obtained were carried out in sulfonation equipment, as detailed'in Fig. 1 in the paper of T. H. Liddicoet and S. A. Olund, Journal of American Oil Chemists Society, Vol. 40, No. 1, pages 5-10 (1963).

The experimental procedure employed was in accordance with the standardized batch oleum sulfonation procedure of the reference, except for the following changes:

(1) a nitrogen atmosphere was maintained; (2) digestion temperatures and times were: (a) mild sulfonationto F. for minutes, and (.b) severe sulfonation-120 F. for 60 minutes; and

(3) setting temperatures and times were: (a) mild sulfonation to F. for 120 minutes,

and

(b) severe sulfonationto F. for 60 minutes.

In both the mild and severe sulfonation treatments, the subsequent processing steps were the same as indicated in the reference. The experimental color values for the finished alkylbenzene sulfonate products are those values obtained for 2 percent by weight sulfonate solutions expressed in terms of percent saturation, using the internationally defined ICI tri-stimulus, Hardy, A. C., Handbook of Colorimetry, The Technology Press, MIT, Cambridge, Massachusetts, 1936, and the procedure is described by R. House and J. L. Darragh, Analytical Chemistry, vol. 26, page 1492 (1954).

3 Examples 1-11 POLYPROPYLENE TETRAMER BENZENE ALKYLATE [Av. mol. wt. 242-245, 22% oleum] Mild Sull'onation, N Atmosphere From the above examples, it is to be seen that whether the sulfonation conditions be mild or severe, the presence of cnmene (Runs 1, 2, 3, 10, and 11) improves the product color. Thus, Run 2 yields a color about 30 percent better than Run 1, and Run 11 is about 42% better than Run 10. From a comparison of Runs 4--9, inclusive, it is to be seen that as little as 0.5 wt. percent of added acetic acid used with cumene causes an appreciable improvement in product color, whereas little added improvement is to be expected by using amounts of acetic acid in excess of 6%. Run 8 shows that the color improvement can exceed 50%.

Examples 12-20 POLYPROPYLENE PENIAMER BENZENE ALKYLA'IE [Av. mol. wt. 264-267, 22% oleum] Mild Sulfonation, N Atmosphere As in the case of Runs 1-11, inclusive, it is to be seen from Runs 12 20 above, made with polypropylene pentamer, that the oleum sulfonations of branched-chain alkylbenzenes are improved in large measure by effecting these sulfonations in the presence of added acetic acid and lower alkylbenzenes.

This invention has been described with particular reference to preferred embodiments thereof; nevertheless, it will be understood that variations in these embodiments can be eifected without departing from the inventive concept.

I claim:

1. In a process for producing a branched-chain monoalkylbenzene sulfonate detergent at a temperature in the range from about 50 to F. by sulfonating with oleum a branched-chain monoalkylbenzene hydrocarbon having from 9 to 18 carbon atoms in its alkyl chain, the improvement which comprises sulfonating said alkylbenzene in the presence of from 0.5 to 6.0 weight percent each, based upon the Weight of the branched-chain alkyl-benzene, of acetic acid and of a lower alkylbenzene represented by the formula:

wherein R and R is methyl, ethyl, or propyl and thereby producing branched-chain monoalkylbenzene sulfonates having improved color and odor characteristics.

2. In the production of branched-chain monoalkylbenzene sulfonate detergent at a temperature in the range from about 50 to 150 F. by sulfonating with oleum a branched-chain monoalkylbenzene hydrocarbon having a side chain of from 9 to 18 carbon atoms, the improvement which comprises sulfonating said alkylbenzene in the added presence of from about 0.5 to 6.0 weight percent each, based upon the weight of the alkylbenzene, of acetic acid and of cumene, thereby producing branched-chain monoalkylbenzene sulfonates having improved color and odor characteristics.

References Cited by the Examiner UNITED STATES PATENTS 2,694,086 11/1954 Mitchell et a1 260505 2,704,295 3/1955 Gilbert et al. 260505 2,820,015 1/ 1958 Smith 260505 2,831,020 4/1958 Norwood et al 260505 2,889,360 6/1959 Brooks 260505 2,897,156 7/1'959 Lewis 260505 2,928,867 3/1960 Kirk et al 260505 3,042,713 7/1962 Schar 260505 OTHER REFERENCES Groggins, Unit Processes in Organic Chemistry, 5th .edition, 1958, pp. 310-311.

LORRAINE A. WEINBERGER, Primary Examiner. LEON ZITVER, Examiner. B. EISEN, M. WEBSTER, Assistant Examiners. 

1. IN A PROCESS FOR PRODUCING A BRANCHED-CHAIN MONOALKYLBENZENE SULFONATE DETERGENT AT A TEMPERATURE IN THE RANGE FROM ABOUT 50 TO 150*F. BY SULFONATING WITH OLEUM A BRANCHED-CHAIN MONOALKYLBENZENE HYDROCARBON HAVING FROM 6 TO 18 CARBON ATOMS IN ITS ALKYL CHAIN, THE IMPROVEMENT WHICH COMPRISES SULFONATING SAID ALKYLBENZENE IN THE PRESENCE OF FROM 0.5 TO 6.0 WEIGHT PERCENT EACH, BASED UPON THE WEIGHT OF THE BRANCHED-CHAIN ALKYLBENZENE, OF ACETIC ACID AND OF A LOWER ALKYLBENZENE REPRESENTED BY THE FORMULA: 